Creating new foraging opportunities for dark-bellied brent Branta bernicla and barnacle geese Branta leucopsis in spring insights from a large-scale experiment

• Main Authors: Bos, D, Stahl, J
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2003
• Subjects: Branta bernicla; Branta leucopsis; salt marsh; agricultural grassland; herbivory; forage quality; disturbance; VEGETATION SUCCESSION; BODY RESERVES; SALT-MARSH; B-BERNICLA; CONSEQUENCES; DEPLETION; brent geese; Brent goose
• Online Access: https://hdl.handle.net/11370/0d80fa86-69be-48cb-85b1-2ddfe9c2d389; https://research.rug.nl/en/publications/0d80fa86-69be-48cb-85b1-2ddfe9c2d389

The implementation of a new non-disturbance policy on Schiermonnikoog (Dutch Wadden Sea islands) provided an experiment to test ideas concerning the switch between habitats by spring-staging Dark-bellied Brent Geese Branta bernicla and Barnacle Geese B. leucopsis. In the experimental years (2000 and 2001) the farmers desisted from all scaring activities in the enclosed pasture area (290 ha) with grasslands intensively managed for dairy farms. The adjoining salt marsh (1635 ha) already was afforded complete protection, and traditionally provided the main goose feeding area in spring. A traditional habitat switch to the marsh coincides with the spring increase of forage production in the marsh habitat, suggesting that forage availability on the marsh is limiting in early spring. Compared to three control years (1997, 98 and 99 with scaring in the pastures) both species of geese extended their usage of the agricultural habitat in the two non-scaring years, where they remained until migratory departure (Apr for the Barnacle Geese, late May for the Dark-bellied Brent). Numbers of geese on the salt marsh did not change, hence non-disturbance triggered an increase of capacity for spring feeding geese at this staging site. The change was most dramatic for the Dark-bellied Brent Goose with a doubling of numbers on the island in the years without scaring, and identification of ringed individuals showed that the birds recruiting to this new spring tradition had in previous seasons utilised other sites in the Dutch Wadden Sea.